Stent graft having an internal bidirectional branch

ABSTRACT

A stent graft having an internal bidirectional branch formed from a tubular segment of graft material. The internal bidirectional branch extends within the lumen of the stent graft and proximally and distally from a lateral opening in the sidewall of the stent graft. The tubular segment from which the stent graft is made is partitioned into first and second sections along a length of the tubular segment to form the internal bidirectional branch. The lateral opening has a length and a width that may be greater than the diameter of the internal bidirectional branch and may be in the shape of a quadrilateral. The internal bidirectional branch and the stent graft are formed from a single piece of graft material.

RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.16/881,269, filed May 22, 2020, which is a continuation of U.S.application Ser. No. 15/652,561, filed Jul. 18, 2017 (now U.S. Pat. No.10,660,770) which are incorporated by reference in their entireties.

BACKGROUND 1. Technical Field

The present invention relates to methods of making an internalbidirectional branch within an endoluminal prosthesis, such as forbranched endovascular procedures.

2. Background Information

Endovascular aortic aneurysm repair is practiced by a wide range ofphysicians across varying specialties. An aortic aneurysm is anenlargement of the aorta of a patient caused by weakening in the wall ofthe aorta. If an aortic aneurysm is untreated, it may rupture and causeserious health complications.

The surgical procedure for endovascular aortic aneurysm repair involvesthe placement of a stent graft within the aorta of a patient to seal offthe aneurysm from blood flow to prevent the aneurysm from expanding.Physicians often use the procedure to treat abdominal aortic aneurysms(AAA), thoracic aortic aneurysms (TAA), thoraco-abdominal aorticaneurysms (TAAA), and aneurysms in other locations of the patient.

The aorta has many branches to other vessels or arteries, such as therenal arteries, the superior mesenteric artery (SMA), the inferiormesenteric artery, and the left and right internal iliac arteries.Branch vessels are also connected to the head, arms, spinal cord,intestines and/or kidneys. Endovascular repair of aneurysms occurring ator near branch vessels requires that blood flow to the branch vessel ismaintained and access to the branch vessel for cannulation is available.

Stent grafts may include internal branches to cannulate branch vesselsand to maintain blood flow to the branch vessels. However, theseinternal branches often only include a small opening or access in onedirection within the stent graft for physicians to cannulate the branchvessel. Often times, it is unknown or not clear which direction thebranch vessel is best cannulated. These factors increase the difficultyof cannulation, which can lead to complications during the surgicalprocedure for endovascular aortic aneurysm repair.

BRIEF SUMMARY

This invention concerns a method of making an internal bidirectionalbranch within an endoluminal prosthesis that enables cannulation of abranch vessel from several directions and allows surgeons the ability toaccess the outside of the endoluminal prosthesis through thebidirectional branch from several directions. The method also provides asimplified construction of an endoluminal prosthesis with abidirectional branch and eliminates the need for making a separatebranch for connection to an endoluminal prosthesis.

The present invention relates to a method of making a bidirectionalbranch within an endoluminal prosthesis. The method includes laying atubular segment of graft material flat. The tubular segment of graftmaterial includes a first lateral edge, a second lateral edge, a widthextending from the first lateral edge to the second lateral edge, and alength extending from a proximal end to a distal end of the tubularsegment. The method also includes partitioning the tubular segment intofirst and second sections along the length of the tubular segment. Thefirst section extends from the first lateral edge toward the secondlateral edge and includes a width less than the width of the tubularsegment. The second section extends from the second lateral edge towardthe first lateral edge and includes a width less than the width of thefirst section such that a total width of the first and second sectionsis the same as the width of the tubular segment. The method alsoincludes partitioning the second section of the tubular segment into atleast three sub-sections. A first sub-section extends from the proximalend toward the distal end for a length, a second sub-section extendsfrom the first sub-section toward the distal end for a length, and athird sub-section extends from the second sub-section to the distal endand has a length. A total length of the three sub-sections is the sameas the length of the tubular segment. The method further includesconnecting the tubular segment along a lateral edge of the firstsub-section from the proximal end to the second sub-section and along alateral edge of the third sub-section from the distal end to the secondsub-section. The lateral edges of the first and third sub-sections areopposite the second lateral edge of the tubular segment. The method alsoincludes turning the tubular segment inside out such that the first,second and third sub-sections of the second sub-section form thebidirectional branch, the bidirectional branch is positioned within alumen of the endoluminal prosthesis, and an opening of the thirdsub-section is exposed.

A method of making an internal bidirectional branch for an endoluminalprosthesis from a tubular segment of graft material. The method includespartitioning a tubular segment of graft material into two tubularsections. The tubular segment of graft material having a lumen, adiameter, and a length extending from a proximal end to a distal end ofthe tubular segment. Each tubular section having the same length as thetubular segment of graft material. The first tubular section includes adiameter less than the diameter of the tubular segment of graftmaterial, and the second tubular section includes a diameter less thanthe diameter of the first tubular section such that a total diameter ofthe first and second tubular sections is the same as the diameter of thetubular segment of graft material. The method also includes partitioningthe second tubular section into five sub-sections along the length ofthe tubular segment of graft material, wherein a total length of thefive sub-sections is the same as the length of the tubular segment ofgraft material. A first sub-section extends from the proximal end towardthe distal end for a length, a second sub-section extends from the firstsection toward the distal end for a length, a third sub-section extendsfrom the second sub-section toward the distal end for a length, a fourthsub-section extends from the third sub-section toward the distal end fora length, and a fifth sub-section extends from the fourth section to thedistal end and has a length. The method also includes connecting thetubular segment of graft material along the first, second, fourth, andfifth sub-sections of the second tubular section to separate the firsttubular section and the second tubular section and removing the firstand fifth sub-sections of the second tubular section from the tubularsegment while maintaining connected edges of the first and fifthsub-sections such that the second, third and fourth sub-sections formthe bidirectional branch. The method further includes turning thetubular segment inside out such that the bidirectional branch ispositioned within a main lumen of the endoluminal prosthesis and anopening of the third sub-section is exposed.

A method of making an internal bidirectional branch for an endoluminalprosthesis including laying a tubular segment of graft material flat.The tubular segment of graft material includes a first lateral edge, asecond lateral edge, a width extending from the first lateral edge tothe second lateral edge, and a length extending from a proximal end to adistal end of the tubular segment. The method also includes partitioningthe tubular segment into first and second sections along the length ofthe tubular segment. The first section extends from the first lateraledge toward the second lateral edge and has a width less than the widthof the tubular segment, and the second section extends from the secondlateral edge toward the first lateral edge and has a width less than thewidth of the first section such that a total width of the first andsecond sections is the same as the width of the tubular segment. Themethod also includes partitioning the second section of the tubularsegment into at least three sub-sections, wherein each section has thewidth of the second section. A first sub-section extends from theproximal end toward the distal end for a length, a second sub-sectionextends from the first sub-section toward the distal end for a length,and a third sub-section extends from the second section to the distalend and has a length. A total length of the five sections is the same asthe length of the tubular segment. The method further includesconnecting the tubular segment along a lateral edge of the firstsub-section from the proximal end to the second sub-section and along alateral edge of the third sub-section from the distal end to the secondsub-section. The lateral edges of the first and third sub-sections areopposite the second lateral edge of the tubular segment. The method alsoincludes turning the tubular segment inside out such that the first,second and third sub-sections of the second section form thebidirectional branch, the bidirectional branch is positioned within alumen of the endoluminal prosthesis, and an opening of the third sectionis exposed. The method also includes connecting a plurality of stents toan exterior surface of the endoluminal prosthesis.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a flattened perspective view of a tubular segment of graftmaterial;

FIG. 2 shows a flattened perspective view of the tubular segment ofgraft material of FIG. 1 separated into first and second tubularsections;

FIG. 3 shows a flatten perspective view of the tubular segment of graftmaterial of FIG. 1 with two sub-sections of the second tubular sectionremoved to form a bidirectional branch;

FIG. 4 shows a perspective view of turning the tubular segment of graftmaterial of FIG. 1 inside out;

FIG. 5 shows a side view of the tubular segment of graft material ofFIG. 1 after being turned inside out;

FIG. 6 shows a side view of the tubular segment of graft material ofFIG. 1 after being turned inside out with a plurality of stents;

FIG. 7 shows an alternate side view of the tubular segment of graftmaterial of FIG. 1 after being turned inside out and cut to expose freeedges of an opening of the bidirectional branch;

FIG. 8 shows an alternate side view of the tubular segment of graftmaterial of FIG. 1 turned inside out and after attaching the free edgesof the opening of the bidirectional branch to the graft material and/orplurality of stents;

FIG. 9 shows a cross-sectional side view of the endoluminal prosthesiswith the internal bidirectional branch of FIG. 8 taken along lines 9-9;

FIG. 10 shows an end view of the endoluminal prosthesis with theinternal bidirectional branch of FIG. 8 taken along lines 10-10; and

FIG. 11 shows a perspective view of cannulating the endoluminalprosthesis with the internal bidirectional branch in at least twodirections.

DETAILED DESCRIPTION OF THE DRAWINGS AND THE PRESENTLY PREFERREDEMBODIMENTS

In the present disclosure, the term “proximal” refers to a directionthat is generally closest to the heart during a medical procedure, whilethe term “distal” refers to a direction that is farthest from the heartduring a medical procedure.

The term “prosthesis” refers to any device for insertion or implantationinto or replacement for a body part or a function of that body part. Theterm also may refer to a device that enhances or adds functionality to aphysiological system. The term prosthesis may include, for example andwithout limitation, a stent, stent-graft, filter, valve, balloon,embolization coil, and the like.

FIG. 1 shows a tubular segment 10 of graft material. The tubular segment10 includes a tubular body 12, a proximal end 16, a distal end 18, afirst surface 20, a second surface 22, a length 24 that extends from theproximal end 16 to the distal end 18, and a lumen 26. The tubularsegment 10, as shown in FIG. 1 , has been flattened. In the flattenedstate, the tubular segment 10 also includes a width 14, a first or leftlateral edge 28 and a second or right lateral edge 30. In anon-flattened state, the tubular segment 10 has a diameter. The graftmaterial of the tubular segment 10 may include a flexible material, suchas polytetrafluoroethylene (PTFE) or expanded PTFE (ePTFE), polyethyleneterephthalate (PET), a polyester material, or other stent graftmaterials known in the art.

To form an endoluminal prosthesis with an internal bidirectional branch48, the tubular segment 10 of graft material is separated into twotubular sections 32, 34 along a partition line 40. Each of the first andsecond tubular sections 32, 34 has the same length 24 as the tubularsegment 10. The first tubular section 32 has a width 36 in the flattenedstate and a diameter in the non-flattened state. The width 36 anddiameter of the first tubular section 32 is less than the width 14 anddiameter of the tubular segment 10. The width 36 of the first tubularsection 32 extends from the left lateral edge 28 toward the rightlateral edge 30 of the tubular segment 10. The second tubular section 34has a width 38 in the flattened state and a diameter in thenon-flattened state. The width 38 and diameter of the second tubularsection 34 is less than the width 36 and diameter of the first tubularsection 32. The width 38 of the second tubular section 34 extends fromthe right lateral edge 30 toward the left lateral edge 28, or, in otherwords, from the first tubular section 32 to the right lateral edge 30.The combined or total width of the first and second tubular sections 32,34 is the same as the width 14 of the tubular segment 10.

The first or left lateral edge of the first tubular section 32 is thesame as the left lateral edge 28 of the tubular segment 10, and thesecond or right lateral edge of the first tubular section 32 is thepartition line 40. The first or left lateral edge of the second tubularsection 34 is the partition line 40, and the second or right lateraledge of the second tubular section 34 is the same as the right lateraledge 30 of the tubular segment 10.

To form the internal bidirectional branch 48, the second tubular section34 is separated into five sections or sub-sections 34 a, 34 b, 34 c, 34d, and 34 e, as shown in FIG. 1 . Each sub-section 34 a, 34 b, 34 c, 34d, and 34 e has the same width 38 as the second tubular section 34. Thefirst sub-section 34 a extends from proximal end 16 toward the distalend 18 for a length, the second sub-section 34 b extends from the firstsub-section 34 a toward the distal end 18 for a length, the thirdsub-section 34 c extends from the second sub-section 34 b toward thedistal end 18 for a length, the fourth sub-section 34 d extends from thethird sub-section 34 c toward the distal end 18 for a length, and thefifth sub-section 34 e extends from the fourth sub-section 34 d to thedistal end 18 and comprises a length. As shown in FIGS. 1-3 , the lengthof the third sub-section 34 c may be greater than the lengths of thefirst, second, fourth and fifth sub-sections 34 a, 34 b, 34 d, 34 e,which are approximately equal. In other examples, the lengths of eachsub-section 34 a, 34 b, 34 c, 34 d, and 34 e may be the same or mayvary, e.g., depending on a desired axial length of the bidirectionalbranch 48 relative to the overall axial length of the endoluminalprosthesis, or other considerations.

To separate the first and second tubular sections 32, 34, the tubularsegment 10 is connected along the partition line 40 within the first,second, fourth and fifth sub-sections 34 a, 34 b, 34 d, 34 e of thesecond tubular section 34. The tubular segment 10 is connected viasewing or stitching the tubular segment 10 along the partition line 40,as shown in FIG. 2 . The tubular segment 10 remains unconnected alongthe partition line 40 within the third sub-section 34 c to create anopening 44 for the second tubular section 34 that is described infurther detail below. The separation of the first and second tubularsections 32, 34 creates a lumen 42 of the second tubular section 34.

The second, third, and fourth sub-sections 34 b, 34 c, 34 d form theinternal bidirectional branch 48 and therefore the first and fifthsub-sections 34 a, 34 e are removed. The first and fifth sub-sections 34a, 34 e of the second tubular section 34 are removed from the tubularsegment 10 by cutting adjacent to the partition line within the firstand fifth sub-sections 34 a, 34 e and along respective ends of the firstand fifth sub-sections 34 a, 34 e adjacent to the second sub-section 34b and the fourth sub-section 34 d, respectively. As shown in FIG. 3 ,during the cutting and removal of the first and fifth sub-sections 34 a,34 e, the sewn partition line 40 within the first and fifth sub-sections34 a, 34 e is maintained such that the first tubular section 32 is notopen or otherwise exposed along the partition line 40 where the firstand fifth sub-sections 34 a, 34 e previously were connected.

In an alternative embodiment (not shown), to form the internalbidirectional branch, the second tubular section 34 is separated intothree sections or sub-sections rather than five sections or sub-sectionssuch that the first sub-section comprises sub-sections 34 a and 34 b ofthe previously described embodiment, the second sub-section comprisessub-section 34 c of the previously described embodiment, and the thirdsub-section comprises sub-sections 34 d and 34 e of the previouslydescribed embodiment. In addition to comprising three sub-sectionsrather than five sub-sections, the first and third sub-sections of thealternative embodiment may not be cut and removed. In this alternativeembodiment, the internal bidirectional branch would comprise a lengththat is equal to the length 24 of the tubular segment 10. The method ofmaking the alternative embodiment of bidirectional branch wouldotherwise include the same steps described above and below regarding theendoluminal prosthesis comprising the internal bidirectional branch 48.

To support the patency and shape of the internal bidirectional branch48, wire 50 is added to the internal bidirectional branch 48, as shownin FIG. 3 . Wire 50 may include nitinol wire or a bow wire and is addedvia stitching or sewing wire 50 to the graft material of the tubularsegment 10. Wire 50 is added to the internal bidirectional branch 48around proximal and distal ends of the second and fourth sub-sections 34b, 34 d, as shown in FIG. 3 , and along the right lateral edge 30 withinthe second and fourth sub-sections 34 b, 34 d. Wire is also added alongthe right lateral edge 30 within the third sub-section 34 c. In oneexample, nitinol wire is added to the internal bidirectional branch 48around proximal and distal ends of the second and fourth sub-sections 34b, 34 d and along the right lateral edge 30 within the second and fourthsub-sections 34 b, 34 d, and a bow wire is added along the right lateraledge 30 within the third sub-section 34 c. In other examples, wire 50may be added at additional locations or areas on the second and fourthsub-sections 34 b, 34 d to support the shape of the internalbidirectional branch 48.

After removal of the first and fifth sub-sections 34 a, 34 e and theaddition of wire 50 to the internal bidirectional branch 48, the tubularsegment 10 is turned inside out to form an endoluminal prosthesis 54, asshown in FIG. 4 , such that the internal bidirectional branch 48 islocated inside or internally within a main lumen 46 of the endoluminalprosthesis 54. Prior to turning the tubular segment 10 inside out, thefirst surface 20 of the first tubular section 32 was located on theexterior of the tubular segment 10 and the second surface 22 of thefirst tubular section 32 was located on the interior of the tubularsegment 10, as shown in FIGS. 1-3 . After the tubular segment 10 isturned inside out, the second surface 22 of the first tubular section 32forms the exterior of the endoluminal prosthesis 54 and the firstsurface 20 of the first tubular section 32 forms the interior of theendoluminal prosthesis 54.

FIG. 5 shows a side view of the endoluminal prosthesis 54 with theinternal bidirectional branch 48 located internally within the mainlumen 46 of the endoluminal prosthesis 54. After turning the tubularsegment 10 inside out, the opening 44 of the internal bidirectionalbranch 48 is exposed. As shown in FIG. 5 , the opening 44 forms anoval-shaped slit prior to expansion, which is described in detail below.

A plurality of stents 52 may be added to the exterior of the endoluminalprosthesis 54, which is the second surface 22 of the first tubularsection 32, to support the shape of the endoluminal prosthesis 54 and tofacilitate positioning of the endoluminal prosthesis 54 within theaorta. The plurality of stents 52 may include Z-stents, Gianturco stentdesign or other stent designs. In one example, as shown in FIG. 6 , theplurality of stents 52 connected to the endoluminal prosthesis 54 areZ-stents.

Each Z-stent may include a series of substantially straight segments orstruts interconnected by a series of bent segments or bends. The bentsegments may include acute bends or apices. The Z-stents are arranged ina ZigZag configuration in which the straight segments are set at anglesrelative to one another and are connected by the bent segments. Thisdesign provides both significant radial force as well as longitudinalsupport. In tortuous anatomy, branches, or fenestrations, it may bepreferable to use alternative stents or modifications to the Z-stentdesign to avoid stent-to-stent contact. Alternative stents may include,for example, annular or helical stents. Furthermore, in complexanatomical situations, external stents may have the potential to becomeintertwined with the wires or other devices utilized to ensure branchvessel access, sealing, and fixation. Thus, in some instances, it may bedesirable to affix some of the stents 52 to the interior or firstsurface 20 of the first tubular section 32 and/or to exterior andinterior surfaces of the internal bidirectional branch 48.

The plurality of stents 52 include at least two rows 62, 64 of stents,as shown in FIG. 6 . The plurality of stents 52 are positioned aroundthe opening 44 of the internal bidirectional branch 48 such that an apex60 of the first row 62 of Z-stents align with a proximal end 56 of theopening 44 and an apex 60 of the second row 64 of Z-stents align with adistal end 58 of the opening 44, as shown in FIG. 6 . In thisconfiguration, the Z-stents form a quadrilateral around the opening 44.The quadrilateral may include the shape of a parallelogram and/or arhombus.

FIG. 7 shows a side view of the endoluminal prosthesis 54 with theinternal bidirectional branch 48. To increase the size of the opening 44to allow access to the internal bidirectional branch 48 from severaldirections, the graft material surrounding the opening 44 and within thequadrilateral formed between the first and second rows 62, 64 ofZ-stents surrounding the opening 44 are puckered to facilitate cuttingthe graft material adjacent to the Z-stents and within thequadrilateral. Specifically, for illustrative purposes, FIG. 7 shows acutting line 66 that begins at the apex 60 a of the second row 64 ofZ-stents adjacent to the distal end 58 of the opening 44 and continuesalong a straight segment 68 of the second row 64 of Z-stents away fromthe opening 44 until the subsequent apex 60 b of the second row 64 ofZ-stents. The cutting line 66 then extends from the apex 60 b of thesecond row 64 of Z-stents to the adjacent apex 60 c of the first row 62of Z-stents and continues along a straight segment 68 of the first row62 of Z-stents toward the opening 44 until the apex 60 d of the firstrow 62 of Z-stents adjacent to the proximal end 56 of the opening 44. Acorresponding cutting line is located on the opposite side of theopening 44 (not shown).

The exterior of the graft material is cut along the cutting line 66 onboth sides of the opening 44 such that free edges 70 of the graftmaterial are formed. The opening 44 is increased to be the size of thequadrilateral between the first row 62 and the second row 64 of Z-stentsby opening and/or pushing the graft material inward toward the interiorof the main lumen 46 of the endoluminal prosthesis 54, and then the freeedges 70 of the graft material are attached to the graft material and/orthe stents 52 where the graft material was initially cut, as shown inFIG. 8 . The free edges 70 may be connected to the graft material nearthe stents 52 via tacks to facilitate stitching or sewing of the freeedges 70 back to the graft material near the stents 52 and/or to thestents 52. During stitching or sewing, the tacks may be removed. FIG. 8shows a sewing line 72 where the free edges 70 are connected to thegraft material near the stents 52 and/or to the stents 52. FIG. 8 alsoshows the increased size of the opening 44 that mirrors the size of thequadrilateral between the first and second rows 62, 64 of Z-stentsbetween the apices 60 of the Z-stent located near the proximal anddistal ends 56, 58 of the opening 44. In other examples, when differentstent shapes are used, the opening 44 may be similarly puckered, cut andattached to the graft material and/or stents 52 to mirror the shapebetween two rows of stents 52 and to increase the size of the opening 44of the internal bidirectional branch 48 to facilitate ease ofcannulation and the ability to access the internal bidirectional branch48 from the exterior of the endoluminal prosthesis 54 from severalangles or directions.

FIG. 9 shows a cross-sectional side view of the internal bidirectionalbranch 48 positioned internally within the main lumen 46 of theendoluminal prosthesis 54, and FIG. 10 shows an end view of the internalbidirectional branch 48 with the main lumen 46 of the endoluminalprosthesis 54. With the construction and positioning of the internalbidirectional branch 48, during cannulation, a cannula or tube may beinserted through the opening 44 of the internal bidirectional branch 48and then exit the internal bidirectional branch 48 either through adistal end 74 of the internal bidirectional branch 48 toward the distalend 18 of the endoluminal prosthesis 54 or through a proximal end 76 ofthe internal bidirectional branch 48 toward the proximal end 16 of theendoluminal prosthesis 54. Alternatively, the cannula or tube may beinserted through the internal bidirectional branch 48 either through thedistal end 74 and out of the opening 44 or through the proximal end 76of the internal bidirectional branch 48 and out of the opening 44. Thearrows 78 in FIG. 9 show the respective two directions that a cannula ortube may exit the internal bidirectional branch 48.

FIG. 11 shows a perspective view of two cannulas or tubes 80 insertedthrough the opening 44 of the internal bidirectional branch 48 with onetube 80 extending out of the distal end 74 of the internal bidirectionalbranch 48 and the distal end 18 of the endoluminal prosthesis 54 and thesecond tube 80 extending out of the proximal end 76 of the internalbidirectional branch 48 and the proximal end 16 of the endoluminalprosthesis 54.

Advantageously, the present embodiments allow for the construction of anendoluminal prosthesis with an internal bidirectional branch from asingle piece of graft material. The simplified construction decreasesthe number of materials, costs, and manufacturing time to make anendoluminal prosthesis with an internal bidirectional branch. Thesimplified construction also eliminates the need for making a separatebranch for connection to the endoluminal prosthesis. The simplifiedconstruction also decreases interference of multiple tubes or cannulaswithin the lumen of the endoluminal prosthesis.

As another advantage, the present embodiments enable cannulation of abranch vessel from several directions. Specifically, the enlargedopening of the internal bidirectional branch allows access to one ormore the branch vessels and decreases the complexity of the trying tocannulate through a small opening. Also, for patients with closelyspaced branch vessels, the enlarged opening of the internalbidirectional branch allows for multiple cannulas and/or tubes to beinserted through the opening. The enlarged opening of the internalbidirectional branch also allows cannulation is multiple directions whenit may not be clear if the vessel is best cannulated from one direction.

As another advantage, the present embodiments enable cannulation throughat least two directions within the internal bidirectional branch.Specifically, cannulation may occur through either the proximal ordistal ends of the internal bidirectional branch. The multiple exits ofthe internal branch allows for the insertion of multiple cannulas ortubes with decreased interference within the internal bidirectionalbranch and the ability to access the branched vessel from differentdirections within the endoluminal prosthesis.

It will be appreciated by those skilled in the art that changes could bemade to the embodiments described above without departing from the broadinventive concept therefore. It is understood, therefore, that thisinvention is not limited to the particular embodiments disclosed, but itis intended to cover modifications within the spirit and scope of thepresent invention as defined by the claims.

We claim:
 1. A stent graft comprising: a substantially tubular graft ofgraft material having a proximal end, a distal end, an internal lumen,and a sidewall; an enlarged lateral opening in the sidewall and having aproximal end, a distal end, a length and a width, an internal branchdisposed within the lumen and in fluid communication with the enlargedlateral opening, the internal branch having a proximal end, a proximalend opening, a distal end, a distal end opening, a proximal portionextending from the proximal end of the enlarged lateral opening towardthe proximal end of the substantially tubular graft and having adiameter, and a distal portion extending from the distal end of thelateral opening toward the distal end of the substantially tubular graftand having a diameter; and a plurality of stents; wherein each of thelength and width of the enlarged lateral opening is greater than thediameters of the proximal and distal portions of the internal branch anddefine an enlarged recess into the internal branch; and wherein thesubstantially tubular graft and the internal branch are constructed froma single piece of the graft material.
 2. The stent graft of claim 1,wherein the lateral opening is in the shape of a quadrilateral.
 3. Thestent graft of claim 1, further comprising a wire support about aperimeter of the proximal and distal end openings of the internalbranch.
 4. The stent graft of claim 1, further comprising a longitudinalwire support along the length of the internal branch.
 5. The stent graftof claim 1, wherein the plurality of stents comprises a first stentdisposed proximal of the lateral opening and a second stent disposeddistally of the lateral opening such that a portion of the first stentand a portion of the second stent define a perimeter of the lateralopening.
 6. The stent graft of claim 1, wherein the plurality of stentscomprises a first stent having a first strut, a second strut, and anapex, and a second stent having a first strut, a second strut, and anapex, wherein the first strut, the second strut, and the apex of thefirst stent define the proximal end and first and second proximal sidesof the lateral opening, and the first strut, the second strut, and theapex of the second stent define the distal end and first and seconddistal sides of the lateral opening.
 7. The stent graft of claim 1,wherein the internal branch is a partitioned segment of the sidewall ofthe substantially tubular graft.
 8. A stent graft having an internalbidirectional branch comprising: a substantially tubular graft of graftmaterial having a proximal end, a distal end, an internal lumen, and asidewall; a lateral opening in the sidewall and having a proximal end, adistal end, a length, a width, and a perimeter; an internal branchdisposed within the lumen and in fluid communication with the lateralopening, the internal bidirectional branch having a proximal end, aproximal end opening, a distal end, a distal end opening, a proximalportion extending from the proximal end of the lateral opening towardthe proximal end of the substantially tubular graft and having adiameter, and a distal portion extending from the distal end of thelateral opening toward the distal end of the substantially tubular graftand having a diameter; and a plurality of stents; wherein each of thelength and width of the lateral opening is greater than the diameters ofthe proximal and distal portions of the internal branch and define anenlarged recess into the internal branch; and wherein the internalbranch is an integral partitioned segment of the sidewall of thesubstantially tubular graft.
 9. The stent graft of clam 8, wherein aportion of a first stent and a portion of a second stent define theperimeter of the enlarged lateral opening.
 10. The stent graft of claim8, wherein the substantially tubular graft and the internal branch areconstructed from a single piece of the graft material such that theenlarged lateral opening in the sidewall opens into the internal branchwithout a separate lateral opening in the internal branch.
 11. The stentgraft of claim 8, wherein the lateral opening is in the shape of aquadrilateral.
 12. The stent graft of claim 8, further comprising a wiresupport about a perimeter of the of the proximal and distal end openingsof the internal branch.
 13. The stent graft of claim 8, furthercomprising a longitudinal wire support along the length of the internalbranch.
 14. The stent graft of claim 8, wherein the substantiallytubular graft of graft material and the internal branch are a singlepiece of graft material and where the substantially tubular graft ofgraft material has a first condition where the internal branch isdisposed externally to the substantially tubular graft of graft materialand a second condition where the internal branch is disposed internallyof the substantially tubular graft of graft material.
 15. A stent grafthaving an internal bidirectional branch comprising: a substantiallytubular graft of graft material having a proximal end, a distal end, aninternal lumen, and a sidewall; an enlarged lateral opening in thesidewall and having a proximal end, a distal end, a length, a width, anda perimeter; an internal branch disposed within the lumen and in fluidcommunication with the enlarged lateral opening, the internalbidirectional branch having a proximal end, a proximal end opening, adistal end, a distal end opening, a proximal portion extending from theproximal end of the enlarged lateral opening toward the proximal end ofthe substantially tubular graft and having a diameter, and a distalportion extending from the distal end of the enlarged lateral openingtoward the distal end of the substantially tubular graft and having adiameter; and a plurality of stents; wherein each of the length andwidth of the enlarged lateral opening is greater than the diameters ofthe proximal and distal portions of the internal branch and togetherdefine an enlarged recess into the internal branch; wherein thesubstantially tubular graft and the internal branch are constructed froma single piece of the graft material such that the internal branch is anintegral partitioned segment of the sidewall of the substantiallytubular graft.
 16. The stent graft of claim 15, wherein the plurality ofstents comprises a first stent disposed proximal of the lateral openingand a second stent disposed distally of the lateral opening such that aportion of the first stent and a portion of the second stent define aperimeter of the lateral opening.
 17. The stent graft of claim 15,wherein the proximal portion of the internal branch proximal of theproximal end of the enlarged lateral opening and the distal portion ofthe internal branch distal the enlarged lateral opening are cylindricaland a portion of the internal branch between the proximal and distalportions tapers from a first diameter to a second larger diameter. 18.The stent graft of claim 15, wherein the length of the enlarged lateralopening is greater than the length of the proximal and distal portions.19. The stent graft of claim 17, wherein the portion of the internalbranch between the proximal and distal portions tapers distally from afirst width to a second width greater than the first and tapersproximally from a first width to the second width.
 20. The stent graftof claim 1, wherein the length of the enlarged lateral opening isgreater than the length of the proximal and distal portions.